1. Field of the Invention
The invention relates to the field of sample analysis. More particularly, this invention relates to an apparatus and method for increasing the rate at which microwell plates can be manipulated in performing various experiments.
2. Description of the Related Art
In the field of molecular biology, the process of sequencing nucleic acids has become significant as more and more diseases are linked to genetic abnormalities. The process of identifying genes and their corresponding proteins for potential therapeutic applications is well known.
Other types of molecular biology procedures are also important for therapeutic and research purposes including DNA restriction mapping, DNA probe generation, replication, DNA sample processing, and cycle sequencing. Generally, these procedures involve a substantial number of steps including, without limitation, automated liquid handling, robotic movement of the samples, pipetting of small amounts of many different reagents into a sample, and heating the samples within a given temperature range. These protocols includes a lengthy series of steps which must be performed in the correct order with absolute precision. Further, such assays are often done on multiple samples that require the manipulation of samples in sample carriers in a uniform fashion.
For instance, during clinical analysis of blood chemistry, various reagents and catalysts are mixed with blood samples in given amounts and in particular sequences. This analysis can yield the level of HDL cholesterol, LDL cholesterol, lipids, etc. present in the blood. By having multiple samples in a sample carrier, several samples may be analyzed at any give time. Similarly, in the area of new drug discovery, it is desirable to investigate numerous candidates for therapeutic agents. Given the great number of potential candidates, automated testing is desirable.
Because of the expense of the equipment required to perform these protocols accurately, increasing the throughput of the equipment performing these protocols becomes important for laboratories such as microbiology laboratories. It is desirable to increase the rate at which these protocols are performed while retaining, or even increasing, the quality of performance of the protocols. Automation is one method by which the rate of performing the protocols may be increased. By increasing the rate at which these protocols are performed, the protocols may be performed at a reduced price.
Regardless of the type of experiment to be performed, sample carriers are generally employed so that more than one sample may be processed at any given time. For example, microwell plates are generally utilized in these sample analysis protocols. Microwell plates are plastic plates containing uniformly-spaced cavities for holding various liquids. Generally, these commercially available microwell plates contain eight rows of twelve microwells for an industry-standard ninety-six microwell plate, or sixteen rows of twenty-four microwells for an industry-standard three hundred eighty-four microwell plate. Other sizes are also commercially available.
It is generally known to perform a protocol with automation as follows. Multiple microwell plates are stacked in one location. A transfer mechanism transfers one the of the microwell plates onto a conveyor. The conveyor transports the microwell plate to the desired station, e.g. a pipetting station. The conveyor then takes the microwell plate to the next station, and so on until the desired protocol has been performed on that microwell plate. Upon completion, that microwell plate is transferred by another transfer mechanism to a completion area for further processing.
To transport and store multiple microwell plates, it is known to stack these microwell plates on top of one another. In fact, most microwell plates are designed for stacking.
In many experiments, it is important to maintain a constant, or even a germ-free, environment. Thus, it is often desired to enclose the samples and the automation equipment. Therefore, it is often desired to minimize the size of equipment, thus minimizing the size of the area that needs to be enclosed.
Current microwell stackers, such as the Cartesian Technologies Stacker and Destacker System SD5000, secure a stack of microwell plates on all four corners. This is a disadvantage. Sometimes it is necessary to remove a plate from the middle of a stack of plates. For example, if it is discovered that the plates have been stacked in an incorrect order, a microwell plate located in the middle of the stack may need to be removed. However, because the plates are secured on all four sides, the only way to remove the plate in the middle of the stack is to remove all of the microwell plates above that plate as well. Once the incorrectly loaded plate is removed, the remaining plates must then be reloaded into the stack. This process is inefficient and time-consuming.
Another problem with current stackers is that current stackers are generally fixedly mounted on top of a transfer mechanism. Thus, it is not possible to load the stack of microwell plates in one area, and then locate that stack onto the transfer mechanism: both the stacker and the transfer mechanism must be manipulated together.
Another problem with the current stackers is their inability to determine the orientation of each microwell plate. It is generally known that each microwell plate is typically manufactured such that one of its four corners is chamfered. Yet current stackers are not capable of recognizing the plate orientation. This increases the likelihood that an operation may be performed on the wrong cavity in a plate.
Thus, despite years of effort, the method of manipulating sample carriers such as microwell plates to perform various protocols continues to be slower and more expensive than would be desired.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.